Allow hiding sensors by sensor name
LibrehardwareMonitor recently started reporting the maximum CPU load
across all cores (#381) (https://github.com/LibreHardwareMonitor/LibreHardwareMonitor/pull/1047).
This is pretty redundant for OhmGraphite, which is better equip to slice
and dice the data as desired. Throwing in a virtual sensor kinda mucks
things up.
OhmGraphite has the ability to hide sensors through the sensor ID, and
when I went to look up the sensor ID for this new sensor, I saw:
```
/amdcpu/0/load/1 "CPU Core Max"
```
And then I realized that hiding purely on sensor ID is lackluster when
it would be much clearer to hide based on sensor name.
This commit adds the ability to hide sensors based on name:
```
<add key="CPU Core Max/hidden" />
```